Join CSV files by a common key
Join Two CSV Files by a Common Key
Select a shared column, such as a product code or employee ID, to combine related fields from two CSV files into one row. Both files stay in your browser.
CSV processing stays in your browser
Your files are not uploaded to a server.
File selection
Choose 2 CSV files, up to 50 MiB total. They are processed in left-to-right order. File names and contents are never sent outside your browser.
Drag and drop CSV files here
Up to 2 CSV files, 50 MiB total
Import settings
Auto-detection covers only UTF-8 and Shift_JIS. For CSV files from mainland China, Korea, Taiwan, or Western Europe, select the matching encoding manually.
How it works
Add product names to sales data by product code
How it works
Add product names to sales data by product code
Join matching product-code rows from the sales CSV on the left and the product CSV on the right.
Left CSV
sales.csv
| Product code | Quantity |
|---|---|
| P01 | 2 |
Right CSV
products.csv
| Product code | Product name |
|---|---|
| P01 | Apple |
Output example
| Product code | Quantity | Product name |
|---|---|---|
| P01 | 2 | Apple |
Choose between keeping only matched rows or keeping every row from the left CSV.
Join two CSV files by key
Combine rows that share a key such as Product Code or Employee ID.
Features
- Choose whether to keep only matched rows or every row from the left CSV.
- Match repeated keys and review matched and unmatched row counts.
How it works
- Choose the left CSV, then the right CSV.
- Select one key per file and choose which rows to keep.
- Review the preview and row counts, then download.
Before you start
- Limits: 50 MiB total and one key per file. Blank keys do not match.
- Repeated keys on both sides can increase output rows; deduplicate first if needed.
View FAQs for this tool
Related tools
Refine joined data with Select columns or Filter rows.